An organic light emitting display device and a method of driving the same. In a method of driving an organic light emitting display device including a second capacitor having a first terminal coupled to a gate electrode of a driving transistor and a first capacitor coupled between the gate electrode of the driving transistor and a first power source, the driving method includes supplying a threshold voltage of an organic light emitting diode to a second terminal of the second capacitor during a period when a first current is sunk via the driving transistor, and supplying a data signal to the second terminal of the second capacitor after a voltage corresponding to a difference between a voltage applied to the gate electrode of the driving transistor and the threshold voltage of the organic light emitting diode is charged in the second capacitor.
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1. An organic light emitting display device comprising: a scan driver for sequentially supplying a scan signal to scan lines and sequentially supplying a light-emitting control signal to light-emitting control lines; a data driver for supplying data signals to data lines; pixels at crossing regions of the scan lines and the data lines; and a current sinker coupled to feedback lines for sinking a first current from the pixels, wherein each of the pixels on an i-th horizontal line comprises: an organic light emitting diode; a fourth transistor for controlling an amount of current that flows into a second power source from a first power source via the organic light emitting diode; a first transistor coupled between a gate electrode of the fourth transistor and the data line and configured to turn on when the scan signal is supplied to an i-th scan line of the scan lines; a first capacitor coupled between the gate electrode of the fourth transistor and the first power source; a second capacitor coupled between the gate electrode of the fourth transistor and the first transistor; a second transistor coupled between the gate electrode of the fourth transistor and a second electrode of the fourth transistor, and configured to turn on when the scan signal is supplied to an (i−1)-th scan line of the scan lines; a third transistor coupled between the current sinker and the second electrode of the fourth transistor, and configured to turn on when the scan signal is supplied to the (i−1)-th scan line; and a fifth transistor coupled between an anode electrode of the organic light emitting diode and a common terminal of the first transistor and the second capacitor to supply a threshold voltage of the organic light emitting diode to the common terminal, and configured to turn on when the scan signal is supplied to the (i−1)-th scan line, and wherein i is an integer greater than or equal to 1.
This organic light emitting display (OLED) device uses a scan driver to send scan and light-emission control signals, and a data driver sends data signals. Pixels are located where scan and data lines cross. A current sinker connected to feedback lines pulls current from the pixels. Each pixel includes: an OLED; a transistor (T4) controlling current from a first power source through the OLED to a second power source; a transistor (T1) connecting T4's gate to a data line, activated by the scan signal; a capacitor (C1) between T4's gate and the first power source; a capacitor (C2) between T4's gate and T1; transistors (T2 and T3) connecting T4's second electrode to T4's gate and the current sinker, activated by the previous scan line's signal; and a transistor (T5) connecting the OLED anode to T1/C2, activated by the previous scan line signal, supplying the OLED's threshold voltage to this point.
2. The organic light emitting display device as claimed in claim 1 , further comprising a sixth transistor coupled between the fourth transistor and the organic light emitting diode, and configured to turn off when the light-emitting control signal is supplied.
The OLED display device described in Claim 1, which includes a scan driver sending scan and light-emission control signals, a data driver sending data signals, pixels at scan/data line crossings, a current sinker connected to feedback lines for pulling current from pixels (each with an OLED, transistor T4 controlling current flow through OLED, transistor T1 connecting T4's gate to data line activated by scan signal, capacitor C1 between T4's gate and power source, capacitor C2 between T4's gate and T1, transistors T2/T3 connecting T4's electrode to its gate and the current sinker activated by previous scan line, and transistor T5 connecting OLED anode to T1/C2 to supply OLED threshold voltage), also includes a sixth transistor (T6) between T4 and the OLED. T6 turns off when the light-emission control signal is active, effectively disabling the pixel during its off-state.
3. The organic light emitting display device as claimed in claim 1 , wherein the first current has the same magnitude as current that flows into the organic light emitting diode when a pixel emits light of the highest gray level.
The OLED display device described in Claim 1, which includes a scan driver sending scan and light-emission control signals, a data driver sending data signals, pixels at scan/data line crossings, a current sinker connected to feedback lines for pulling current from pixels (each with an OLED, transistor T4 controlling current flow through OLED, transistor T1 connecting T4's gate to data line activated by scan signal, capacitor C1 between T4's gate and power source, capacitor C2 between T4's gate and T1, transistors T2/T3 connecting T4's electrode to its gate and the current sinker activated by previous scan line, and transistor T5 connecting OLED anode to T1/C2 to supply OLED threshold voltage), has a current sinker that draws a specific amount of current. This current is equal to the current needed to make the OLED emit light at its brightest (highest gray level).
4. The organic light emitting display device as claimed in claim 3 , wherein the current sinker comprises at least three current sources comprising a red current source for sinking current from a red pixel of the pixels, a green current source for sinking current from a green pixel of the pixels, and a blue current source for sinking current from a blue pixel of the pixels.
The OLED display device described in Claim 3, which specifies that the current sinker draws the same current as when a pixel emits at its brightest level, uses a current sinker containing at least three separate current sources: one specifically for red pixels, one for green pixels, and one for blue pixels. This allows individual control of the current sunk from each color subpixel.
5. The organic light emitting display device as claimed in claim 1 , wherein the scan driver is configured to supply the light-emitting control signal to an i-th light-emitting control signal so that the light-emitting control signal is overlapped with the scan signal supplied to the (i−1)-th scan line and the i-th scan line.
In the OLED display device described in Claim 1, including a scan driver sending scan and light-emission control signals, a data driver sending data signals, pixels at scan/data line crossings, a current sinker connected to feedback lines for pulling current from pixels (each with an OLED, transistor T4 controlling current flow through OLED, transistor T1 connecting T4's gate to data line activated by scan signal, capacitor C1 between T4's gate and power source, capacitor C2 between T4's gate and T1, transistors T2/T3 connecting T4's electrode to its gate and the current sinker activated by previous scan line, and transistor T5 connecting OLED anode to T1/C2 to supply OLED threshold voltage), the scan driver sends the light-emission control signal such that it overlaps in time with the scan signals sent to both the previous scan line and the current scan line.
6. A pixel of an organic light emitting display device, the pixel comprising: an organic light emitting diode; a pixel circuit for supplying a current to the organic light emitting diode; a current sinker coupled to the pixel circuit for sinking a first current from the pixel circuit, wherein the pixel circuit comprises: a fourth transistor for controlling an amount of current that flows into a second power source from a first power source via the organic light emitting diode; a first transistor coupled between a gate electrode of the fourth transistor and a data line and configured to turn on when a scan signal is supplied to a scan line; a first capacitor coupled between the gate electrode of the fourth transistor and the first power source; a second capacitor coupled between the gate electrode of the fourth transistor and the first transistor; a second transistor coupled between the gate electrode of the fourth transistor and a second electrode of the fourth transistor, and configured to turn on when the scan signal is supplied to a previous scan line; a third transistor coupled between the current sinker and the second electrode of the fourth transistor, and configured to turn on when the scan signal is supplied to the previous scan line; and a fifth transistor coupled between an anode electrode of the organic light emitting diode and a common terminal of the first transistor and the second capacitor to supply a threshold voltage of the organic light emitting diode to the common terminal, and configured to turn on when the scan signal is supplied to the previous scan line.
A pixel design for an OLED display includes an OLED, a pixel circuit to drive current through the OLED, and a current sinker connected to the pixel circuit to draw a specific current. The pixel circuit includes: a transistor (T4) controlling the current flowing through the OLED; a transistor (T1) linking T4's gate to a data line, which turns on with a scan signal; a capacitor (C1) between T4's gate and a power source; a capacitor (C2) between T4's gate and T1; transistors (T2 and T3) connecting T4's other electrode to T4's gate and the current sinker, enabled by the previous scan line's signal; and a transistor (T5) connecting the OLED's anode to T1/C2 to provide the OLED's threshold voltage, also activated by the previous scan line's signal.
7. The pixel as claimed in claim 6 , wherein the pixel circuit further comprises a sixth transistor coupled between the fourth transistor and the organic light emitting diode, the sixth transistor configured to turn off when a light-emitting control signal is supplied.
The pixel design described in Claim 6, which includes an OLED, a pixel circuit with transistor T4 controlling current, transistor T1 linking T4's gate to data line activated by scan signal, capacitor C1 between T4's gate and power source, capacitor C2 between T4's gate and T1, transistors T2/T3 connecting T4's electrode to its gate and current sinker activated by previous scan line, and transistor T5 connecting OLED anode to T1/C2 for OLED threshold voltage, also includes a sixth transistor (T6) between transistor T4 and the OLED. This sixth transistor is turned off by a light-emitting control signal, effectively switching the pixel off.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
September 7, 2012
September 10, 2013
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